This grant will complete research and conduct clinical trials on our proprietary Smart Variable Geometry Socket (SVGS) system for transfemoral amputees created and simplified in Phase I. SVGS, by maintaining good socket fit at all times, can improve amputee confidence, stability, comfort, hence productivity and, among geriatric amputees, encourage greater activity. The system employs a innovative socket liner and automatic control system yielding comfortable, secure fit of the residual limb in the socket even as the limb changes in volume. Light-weight, simple and requiring no external power, SVGS uses internal pumping action powered by the wearer's walking to adjust liquid bladder volumes automatically. Research proposed includes perfection of materials selection and liner fabrication process, extended human-subject clinical trials with measurement of both physical performance and psychological reaction of the amputee. The project will conclude with workshops, submissions of papers and patent applications. PROPOSED COMMERCIAL APPLICATION: This project will lead to major improvement in lower-limb prostheses by providing the advantage of automatically accommodating diurnal and longer-term volume variations of the residual limb. Because the SVGS is designed for fabrication cost-effectively by prothetists with conventional facilities, we expect wide-spread adoption valued in $l0s of millions annually.